Cristiano Ronaldo insists Portugal have no fear of Brazil ahead of today's World Cup showdown between the two arch rivals.

Ronaldo believes Portugal's 7-0 demolition of North Korea has given Carlos Queiroz's side the belief that they can overcome the tournament favourites and finish top of Group G.

Spain lie in wait for Portugal or Brazil in the last 16, although with the Euro 2008 champions not in action until tonight, neither side will know whether finishing first or second in the group will enable them to avoid them.

But former Manchester United star Ronaldo said Portugal are determined to send out a message to the rest of the field in South Africa, by subjecting Brazil to their first defeat of the tournament.

"We fear nobody," said Ronaldo. "After the performance we gave against North Korea, we believe we can overcome Brazil. And it's not often that we have been in a position to say that. Before we played North Korea, everybody asked about a lack of goals.

"People said that I couldn't score because I had been made captain, and people said the team would struggle to score. But they're not asking those same questions now. We're not playing Brazil just to lose.

"We're playing them to win and to show people what we are capable of achieving at this World Cup. Playing Brazil will be a complicated game against the best team in the world. But this Portugal team believes in itself and we feel we can play well against them."

Portugal's task in beating Brazil is put in context when examining their record against the five-times world champions, which contains just four wins in 18 encounters, including a 6-2 thrashing the last time the two sides met, in Brasilia in November 2008.

There is a fierce rivalry between the two nations, with the fact there are three Brazil-born players - Deco, Pepe and Liedson - in the Portugal squad giving the potentially epic encounter another intriguing edge.

Brazil will be without playmaker Kaka, suspended following his controversial dismissal in the 3-1 triumph over Ivory Coast. With a 100 per cent record so far in South Africa, Brazil head the group, two points clear of second-placed Portugal, who need a win to ensure top spot.

And Kaka warned Portugal there will be no easing off from Brazil, "We will go out to win," said Kaka. "This final group game is important for us to finish first. A draw would also be good, but a win would give us the strength to go into the knockout round really motivated.

"There is a little bit of rivalry between Brazil and Portugal. There are three Brazilian-born players in their side and Portugal is one of the teams we have faced more times in recent years. We thrashed them in Brasilia, but we also lost 2-0 to them in London.

"So you never know what can happen. Portugal drew against Ivory Coast and Spain lost against Switzerland. Football is like that. At times you find adversity and you don't know how a game will develop. But I do hope that the fans get to see a great game on Friday."

Despite his side's emphatic win over North Korea, Portugal boss Queiroz said his players must step up another gear - starting against Brazil. "We must be more ambitious for the next phase," said Queiroz.

"We made certain changes against North Korea and against Brazil we must be physically ready to play. The result of reaching the last 16 is a prize for the motivation we have shown here and the focus we need for the next game.

"It's the same formula for all competitions. We need to be serious, we need to fight and show the will to win. We must do that, but it's also important the players feel free to express their freedom and their joy and their ability to play football. We're capable of putting so much into this tournament."